Legal Question in Family Law in Illinois

Child Support is only retroactive to the date of filing of the Petition for an increase in support so you don't have to worry about that. On the other hand, post-high school education is handled somewhat differently and is generally on a 50/50 or 30/30/30 basis based on the total expense of college education. It could be more or less than the amount you are currently paying for child support. Once your step-daughter turned 18 or graduated high school whichever came later, your husband's obligation to pay child support ceased and should have been terminated by the court.

May I suggest that you file a motion with the court to terminate the child support retroactive to the above and file a Petition for College Contribution to cover the child's college expenses. Either parent can bring such a Petition and the assets/income of both parents are considered in determining the parent's contribution. Also the assets/income of the child can be considered. Under the statute the parent has a right to be informed about grades but the child doesn't have to have "good" grades, just be in good standing with the college or university. This is usually interpreted to be a "C" average. Also, since the "child" is no longer a minor the parenting agreement respecting the tax exemption is no longer controlling and if the mother/step-father contributed more than 50% of her support then they are entitled to claim the exemption, not you and your husband. If the daughter earned more than $3000 for the year and files her own tax return, neither of you can claim her as a dependent.

It seems to me that both sides should lower their voices and try and work out a mutually agreeable arrangement that protects your step-daughter while providing for her college.